In a mobile communication system of the LTE (Long Term Evolution), transmission of “RA Preamble” in “RA (Random Access)” procedure for transmitting a signal relating to transmission processing (including location registration processing, this also applies hereinafter) such as, for example, location registration processing signaling (MO-signalling) and U-plane transmission processing signaling (MO-data) can be restricted by a mobile station UE in the RRC_IDLE state (idle state) by using a mechanism of ACB (Access Class Barring).